import { $getListDepth, $isListItemNode, $isListNode } from '@lexical/list'
import { useLexicalComposerContext } from '@lexical/react/LexicalComposerContext'
import {
  RangeSelection,
  $getSelection,
  $isElementNode,
  $isRangeSelection,
  COMMAND_PRIORITY_CRITICAL,
  ElementNode,
  INDENT_CONTENT_COMMAND,
} from 'lexical'
import { useEffect } from 'react'

type Props = Readonly<{
  maxDepth: number | null | undefined
}>

function getElementNodesInSelection(selection: RangeSelection): Set<ElementNode> {
  const nodesInSelection = selection.getNodes()

  if (nodesInSelection.length === 0) {
    return new Set([selection.anchor.getNode().getParentOrThrow(), selection.focus.getNode().getParentOrThrow()])
  }

  return new Set(nodesInSelection.map((n) => ($isElementNode(n) ? n : n.getParentOrThrow())))
}

function isIndentPermitted(maxDepth: number): boolean {
  const selection = $getSelection()

  if (!$isRangeSelection(selection)) {
    return false
  }

  const elementNodesInSelection: Set<ElementNode> = getElementNodesInSelection(selection)

  let totalDepth = 0

  for (const elementNode of elementNodesInSelection) {
    if ($isListNode(elementNode)) {
      totalDepth = Math.max($getListDepth(elementNode) + 1, totalDepth)
    } else if ($isListItemNode(elementNode)) {
      const parent = elementNode.getParent()

      if (!$isListNode(parent)) {
        throw new Error('ListMaxIndentLevelPlugin: A ListItemNode must have a ListNode for a parent.')
      }

      totalDepth = Math.max($getListDepth(parent) + 1, totalDepth)
    }
  }

  return totalDepth <= maxDepth
}

export default function ListMaxIndentLevelPlugin({ maxDepth }: Props): null {
  const [editor] = useLexicalComposerContext()

  useEffect(() => {
    return editor.registerCommand(
      INDENT_CONTENT_COMMAND,
      () => !isIndentPermitted(maxDepth ?? 7),
      COMMAND_PRIORITY_CRITICAL,
    )
  }, [editor, maxDepth])
  return null
}
